In the field of air filtration, the EN 1822 standard is considered the gold standard for evaluating high-efficiency filters. Originating in Europe in 1998, this standard, after more than two decades of development and refinement, has become a crucial basis for identifying high-quality HEPA filters globally.
I. The EN 1822 standard consists of five parts, each with a different function:
- Part 1: Classification, Performance Testing, and Marking
- Part 2: Aerosol Production, Measuring Equipment, and Particle Count Statistics
- Part 3: Testing Flat Plate Filter Materials
- Part 4: Test Methods for Determining Filter Element Leakage (Scanning Method)
- Part 5: Test Methods for Filter Element This structured approach ensures strict control at every stage, from materials to finished product.
II. Filter Classification System
The EN 1822 standard classifies high-efficiency filters into three main categories:
- EPA filters (High-Efficiency Particulate Air Filters), including grades E10, E11, and E12;
- HEPA filters (High-Efficiency Particulate Air Filters), including grades H13 and H14;
- ULPA filters (Ultra-Low Penetration PA Filters), including grades U15, U16, and U17.
III. Core Concept of MPPS
MPPS (Most Penetrating Particle Size) is a core technical concept of the EN 1822 standard.
It refers to the particle size that a filter is most difficult to capture, typically ranging from 0.1 to 0.3 micrometers.
Why are particles in this range the most difficult to capture? This is because they are small enough to avoid inertial impaction mechanisms, yet lack sufficient Brownian motion to enhance the probability of being captured.
Therefore, the EN 1822 standard requires testing to be conducted on the MPPS of the filter to ensure its effectiveness under the most demanding conditions.
It is worth noting that the droplet nuclei produced by human coughing and sneezing fall precisely within the MPPS range, which explains why H14 HEPA filters are effective at intercepting viral aerosols.
IV. Test Methods and Procedures
EN 1822 specifies a rigorous test procedure, mainly divided into three key stages:
Filter Material Testing
First, a sample of flat-plate filter material is clamped in a test filter holder, and test air is passed through it at a specified flow rate. The generated test aerosol is then added to the test airflow at the inlet to form a homogeneous mixture. A portion of the airflow is collected upstream and downstream using a probe, and the concentration of different particle sizes is recorded to determine the staged collection efficiency curve.
Leakage Testing
Leakage detection of the manufactured filter is performed using a scanning method. The filter is passed through test air and test aerosol at the rated volumetric flow rate, and measurements are taken at the minimum particle size distribution (MPPS) of the filter material. Following DIN EN 1822-2, the entire downstream side of the filter is scanned with a probe, and a computer records the coordinates, velocity, and the measured particle flow rate of the probe.
Efficiency Testing
Finally, the filtration efficiency of the filter needs to be determined. Tests are conducted at the particle size (MPPS) at which the filter material has the lowest separation efficiency, with the filter passing through test air and test aerosols at rated flow rates. For filters of H13 and higher, the standard requires the generation of individual test reports and serial numbers, ensuring that each filter is traceable to its own individual test.
From clean-rooms to operating rooms, the EN 1822 standard acts as a silent guardian, ensuring that every filter performs effectively under the most demanding conditions. It is not merely a set of technical specifications, but a reflection of humanity’s relentless pursuit of clean air. Trenntech is a practitioner of this philosophy; every HEPA filter we offer represents a rigorous fulfillment of our commitment to cleanliness.